Radiophone broadcasting system



Much 9 1926. 1,576,324

J. B. HOGE r-:T AL

RADIOPHONE BROADCASTING SYSTEM Filed August 22, 1922 2 Sheets-Sheet 2 s n E o l K O k g o g G fair/maf `:vw/lav Patented Mar. 9, 1926.

UNITED STATES PATENT OFFICE.

JAMES B. HOGE, OF CLEVELAND, OHIO, AND EDWARD E. CLEMENT, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNORS, BY DIRECT AND MESNE ASSIGNMENTS, T EDWARD F. COLLADAY, 0F WASHINGTON, DISTRICT OF COLUMBIA.

RADIOPHON E BROADCASTING SYSTEM.

Application filed August 22, 1922. Serial No. 583,559.

To all 'whom 'it may concern.'

Be it known that we, JAMES B. Hoen and EDWARD E. CLEMENT. citizens of the United States, residing, respectively, at Cleveland,

in the county of Cuyahoga, State of Ohio,

and Washington, in the District of Columbia, have invented certain new and useful Improvements in Radiophone Broadcasting Systems, of which the following is a specification, reference being had therein to the accompanying drawing.

Our invention relates to radiophone systems, and has for its object to simplify and reduce the cost of such systems when organized for regular commercial operation,

:with special reference to broadcast receiving. It has been proposed to organize such a system on the basis of service, with subscribers stations and a central station, the

central station being equipped with the usual transmitting apparatus and the subscribers stations with receiving apparatus adapted to res ond to the waves transmitted by said centra apparatus. When so used,

a broad range of tuning in the subscribers instruments is unnecessary, and it is possible to depend entirely upon relaying from the central station for waves from other transmitting stations. Where the distances between the central station and the subscribers stations in a local area are relatively short, it is further possible to protect the receiving instruments from atmos heric and other disturbances, and where individual tuning is eliminated disturbances from that source are also eliminated. Such receiving instruments may be simplied and standardized to respond to the modulated waves radiated from their own central station only, and being uniformly tuned and so far as possible exposed to uniform conditions, the central station transmitting apparatus may be adjusted for tuning to the requirements of its subscribers instruments instead of the reverse. In thus tuning the broadcast transmitter, any desired means may be used for ascertaining when the correct wave length is attained, the essential feature being to have a. standard receiving instrument accessible to the transmitting operator, throu h which direct observation can be made an tuning guided. For greater certainty in practice, it has been proposed to extend this principle to the subscribers stations, giving the central station transmitting operator access thereto by means of wire lines to ascertain if the radiophones thereat are functioning properly. Such amplification of tuning methodsl is not claimed herein, however, since any method of determining conditions of mutual resonance is within the scope of our present invention, the gist of which lies in uniformly and permanently tuning the subscribers instruments to a fixed standard wave length, and then adjusting and operating the transmitting apparatus with reference thereto, regardless of the wave lengths of messages received or relayed there y.

A system embodying the presentinvention is indicated in the accompanying drawings, in which:

Fig. 1 is a schematic diagram showing a radiophone system combined with a telephone system, the wire lines to the radio subscribers vstations being the same as the subscribers telephone lines; and

Fig. 2 is a schematic diagram of one such wire line and its connections.

Referring to Fig. 1, the numerals 1, 2 and 3 indicate radiophone receiving stations, for convenience located at the subscribers telephone stations la, 2a and 3a and associated as will presently appear with subscribers lines 4, 5 and 6 leading to the central telephone .station 7, which may contain the usual terminal and connective apparatus for interconnecting the lines. Multiples of the telephone lines may for convenience be carried to a separate radio central switchboard 8, equipped with transmitting apparatus and with such receiving, amplifying, and relaying apparatus as is necessary to give complete service by broadcasting to the area containing the subscribers stations 1, 2, 3. The instruments at the substations are standardized, i. e., they are all uniform in construction and are tuned alike. In Fig. 2 some detail is shown of one such station, which however, is to be taken as typical only. The radiophone receiver may be equipped with a tube detector and two stages of audio amplication to supply the loud speaking receiver 36, in front of which the telephone transmitter T normally hangs. It is necessary to lift the telephone to close the filament circuit through contacts of switch H, and a convenient mounting for the set may have the transmitter T and telephone receiver` t mounted on a common handle containing the switch h, in a well known manner. To enable the operator at the transmittingI station 8 to make observations and determine the accuracy of his tuning, the contacts of both switches H and are closed and the transmitter left in the position shown. The radiophone station l here shown may be located anywhere along the line 4, from the subscribers station to the central station, and the circuit 4 need not be a subscribers telephone circuit but may be a special Wire circuit or a trunk circuit. In the oase of a multi-office telephone system, one radio broadcasting station may serve all the subscribers, and any connection to receiving instruments in different exchange centers must then utilize trunks. The principle remains the same however. If a special wire or wires be employed they should be so arranged that the radio operator can control the radiophone thereon at all times to listen in for tuning.

It will be noted that a loop antenna is shown in Fig. 2. This may be employed in connection with a ground antenna. and 1n any case should be calibrated and set for xed directional receiving from the central station. Thus all the substations will be focussed, so to speak, on the central station, and common tuning, accurate receiving, and stray elimination will be facilitated.

We claim:

In a communication system, a plurality of receiving stations all having receiving apparatus permanently tuned to a fixed standard wave length, a common transmitting station equip ed With transmitting apparatus, means or tuning and operating said transmitting apparatus with reference to the fixed Wave adjustment of said receiving stations, and means controlled from the* transmitjgimo` stntwign for determining when the recepvgggrapparatgs at a regbervingmsktaour signatures.

JAMES B. HOGE. EDWARD E. CLEMENT. 

